SK Hynix may encounter difficulties in hybrid bonding technology. - expreview.com

SK Hynix's hybrid bonding yield struggles are not a routine process hiccup—they expose a structural vulnerability in the HBM4 transition. The physics is unforgiving: copper-to-copper direct bonding demands sub-2nm surface roughness, pushing CMP and wafer planarization to their limits. If yield stays below target, the 16-high stack collapses to 12 or 8 layers, eroding the bandwidth premium that justifies HBM4's pricing. The competitive timing is brutal. Samsung's HBM3E has cleared NVIDIA qualification; Micron targets HBM4 shipments by Q2 2025. A SK Hynix slip in this window invites NVIDIA to accelerate supplier diversification across its B200/GB300 roadmap. The 2023 HBM shortage taught GPU makers the cost of single-source dependency—once that strategic shift locks in, it is nearly irreversible. Over the next 18 months, hybrid bonding equipment orders (BESI, EV Group, Applied Materials) will consolidate around vendors with proven yield data. If SK Hynix cannot close its process-integration gap by end-2025, the HBM market transitions from a one-dominant-player structure to a genuine three-way race. The long-tail effect: advanced packaging IP fragments, and the volume moat SK Hynix built on HBM3E narrows materially by 2027.